Field of the Invention
A prior art filter device is described in U.S. Pat. No. 3,390,778, to Uhen. This filter device includes a container having an inlet opening and an outlet opening and includes a filter unit having a first stage radial flow filter subassembly and having a second stage radial flow filter subassembly. A problem associated with this filter device is that the fluid flow has a relatively excessive number of right angle turns for fluid flow from the inlet opening to the outlet opening, with a resultant head loss.
Other relevant U.S. Pat. Nos. are:
Kasten, 2,766,890, teaches a two-stage fluid demulsifier to separate water droplets from an emulsified liquid using pleated cylindrically-shaped filter paper impregnated with a resinous material to make it resistant to water, gasoline or kerosene and the like, and a fine fibrous mass of material such as fiberglass contained between a perforated metal or wire screen. In operation, the fluid passes radially through both filters. Contaminant seeps downwardly into a contaminant chamber, to be withdrawn from the filter through an outlet. The filter chambers are separated by an annular partition held by bolts. Purified liquid passes upwardly and exits through the outlet.
Fredrickson, 2,960,234, teaches a two-stage water separator. The second stage of the separator has a cartridge which has a previous cylindrical wall which provides support for an external paper separator sheet with puckers throughout which approximately double the amount of paper in a given area. The first compartment has a coalescer cartridge. The compartments are separated by a partition or wall. Flow is radial, i.e., from the outside-in, for each cartridge.
Roosa, 3,105,042, teaches a two-stage liquid fuel filter assembly. In FIG. 4, two identical filter cartridges are axially stacked, each filter having an appropriate filter material, such as a wound cotton cord type. In operation, fluid flows downwardly through the center passageway and then through the lower filter cartridge and then up through the upper filter cartridge and out. In FIG. 5, the lower filter cartridge is a radial flow type filter. In operation, fluid flows downwardly through central passageway and proceeds radially through the lower filter, then upwardly through a large central opening and then flows through the upper filter cartridge. The filter cartridges of the assembly are not replaceable.
Jacobs, et al., 3,132,501, shows in FIG. 5 a dry-cleaning filter assembly having replaceable filter cartridges having a first felt filter stage for removing particulate matter from a dry-cleaning solvent, and a second annular carbon filter for adsorbing dyes and a third annular folded cellulosic filter. As shown by the fluid flow arrows of FIG. 5, fluid passes in through conduit 94, flows downwardly then radially through first filter stage and flows into chamber 160,162 and radially through the second and third filter stage and through opening 168 and out. The filter elements are removable.
Olmos, 3,144,407, teaches a separator for removing moisture from gasoline, and other hydrocarbon liquids, having a first filter cartridge with an outer annular pleated filter paper element and an inner soft batt formed of glass fibers and a second filter cartridge with cylindrical pleated paper coated with phenol formaldehyde to stiffen the paper and silicone to make it water repellant. The filter cartridges are removably secured in the housing. In operation, fluid flows down a center pipe and then radially through the first filter, upwardly and then radially through the second filter and out.
Jumper, 3,465,883, teaches a two-stage fuel water separator and filter, having a first coalescer (FIG. 2) composed of hydrophilic material, e.g. fiberglass and molded into a ring shape and a second separator (FIG. 3) composed of treated filter paper. In operation, fuel passes and flows radially through the coalescer, downwardly through a passageway, and flows radially through the separator and passes out.
Molitor, 3,561,602, teaches a liquid filter, having a first filter element composed of a stack of absorbent cloth discs as shown (FIG. 3) which are saturated with potassium permanganate for dissolving and removing iron from the water, and a second charcoal granular filter for removing odors and the like from the water. In operation, water flows into supply pipe 14 into a lower cylindrical chamber, flows radially through the first filter and then through slots of the central tube, upwardly through the tube and axially through the charcoal filter and out. When the potassium permanganate supply in the first filter becomes exhausted, the filter elements may be replaced with a new element, or the disc filter elements may be re-impregnated by adding an amount of potassium permanganate.
Offer, 3,586,171, teaches a dual-flow, two-stage oil filter. A first filter element is a depth-type filter made from viscose rayon or other synthetic fiber coated with resin and bonded together by heating and curing in a compression mold. A second filter element is made from a fine flow paper. In operation, oil flows radially through both filter elements, with the first filter element excluding particles above 80 microns in size and the second filter element excluding particles above 10 microns in size.
Shaltz, et al., 3,975,273, discloses a two-stage oil filter, having a first depth-type filter media consisting of rayon fibers and a binder and a second surface-type filter media made of spirally wound crepe filter paper. In operation, oil flows in parallel through the filters by passing radially through depth-type filter which removes all solid particles above 90 microns and then through a surface-type filter 30 which removes even smaller solid particles.
Conrad, 4,094,791, teaches an oil filter, having a main flow filter insert and an auxiliary flow filter insert, removable, and replaceable.